1. Field of the Invention
The present invention relates to release sheets for adhesive coated products.
2. Description of Related Art
Release sheets have been made using a wide variety of substrates, including cellulosic materials such as paper and paperboard, polymeric films, and cellulosic materials coated with polymeric films. Release coatings, too, form a diverse categorization--fluorocarbons, chromium complexes, fatty acid amides, long chain hydrocarbon-containing polymers, and various silicone polymers have been found to be useful in the manufacture of release coatings. Among the undercoating layers which have been used are those formed by polyethylene extrudates, by clay-based pigments used in conjunction with water-soluble polymers such as poly(vinyl alcohol), and by starch size press coatings thickened with Kelgin (sodium alginate), carboxymethylcellulose, or polyvinyl alcohol. These under coats are intended to provide "hold out" for the silicone coating and to enhance the smoothness of the base sheet.
U.S. Pat. No. 4,859,511 discloses the use of undercoating layers which are hydrophobic in nature, and are characterized by low tensile strength, low glass transition temperature and low modulus of elasticity. U.S. Pat. No. 4,609,589 is directed to release sheet undercoatings based upon mixtures of certain acrylic resin emulsion compositions.